Under dash relays, and diode question

[ratstalker]

I'm going through my M1009 charging system, and ran across 3 items that I can't clearly figure out from either the trouble shooting guide, or the schematics. My Gen 2 light is out, always has been. I rebuilt both alternators, and they are charging. (Leave well enough alone? ...no...) There is another Bosch relay right behind the instrument cluster/panel. It is the same number as the alternator2 and voltmeter relays. There is also a board above the fuse box that I think is an engine control circuit. Also, I have a three pronged receptacle right next to it without anything in it. Last is a diode right under the glow plug resistor that I can't trace where it goes or what it does. Hopefully, here are the pics:

 

[southdave]

Pic # 2 I got same thing going on. it is a resitor shoved into the socket was wandering my self what and why except mine had huge tape ball.,kind thought it for the tranny

 

[ratstalker]

I figured out picture two, the diode. Mine did indeed have a duct tape ball around it as well. I broke down and disassembled the harness covering. The diode leads to the "water in fuel" sending/sensor unit on the fuel filter assembly. The anode is energized from the starter relay. Interestingly enough, on mine, there are only 3 wires coming out of the "water in fuel" plug. The plug coming from the sender/sensor unit has a weatherproof termination in it, factory installed, so i'm assuming it is a retrofitted sender/sensor. This renders the diode moot in my case. It supplies power to nothing...

You can see the diode in schematic E-1 from TM 9-2320-289-34.

Now, that being said, I'm still trying to figure out why I get no current to my voltmeter. It does work. I just get no current at the plug.

 

[ratstalker]

I was hoping that the diode in picture two, was coming off of "generator 2" relay. Anybody know where this is physically located in the vehicle??? It is on schematic E-9 from TM 9-2320-289-34.

PuZZZZZZZZled...

Just trying to get everything to work. Although I don't have a cure for rust.

 

[southdave]

Hey rat, found this from BigBurb11 may be this help out
"The module is hanging right above the fuse box. It's similar to the glow plug module... but with four terminals.

I think the sender is ok.
Sorry bad info not it, nice to know where that is

 

[ratstalker]

Ok, so more fooling around, a little bit more harness unwrapping and now I magically have a properly working Generator 2 light and properly working voltmeter! Nothing got replaced, or anything. The only thing I did, that I can think of is disconnect and reconnect one connector under the hood. The terminals were REALLY crusty. Perhaps this did it, perhaps some other connection did. I can't say. I still can't figure out what the relay above the steering column is for. PLEEEZE feel free to comment with any knowledge. Here are pics:

 

[ratstalker]

and yes the gen lights both go out right away at idle.

 

[jawalter]

Voltmeter Fix

I fixed my voltmeter by replacing the rectangular ceramic resistor on the back of the voltmeter. My ceramic resistor was "open". I left the original rectangular ceramic resistor that was "open" in place since it acted as an insulator for the ring terminal studs on the back of the voltmeter. I added a new 300 ohm, 5W power resistor in parallel with the original "open" rectangular ceramic resistor. I purchased my resistor from www.mouser.com (part# 660-MOS5C301J). The 300 ohm power resistor in series with the voltage gauge (internal gauge resistance ~190 ohms) is a voltage divider circuit. The 28.6 volts that is supplied to the voltage gauge gets reduced to 10.7 volts by the 300 ohm resistor. The 10.7 volts displays as the ideal "green zone" voltage on the gauge.

I don't know if this will help you fix your voltage gauge problem.

I did have a question about my instrument panel lights. At night when your headlights are on, what lights up on your instrument panel? The only things that light up on my instrument panel are my speedometer, fuel, and voltmeter gauges. My heater controls are dark. Do you think I might have some burnt out bulbs?

Jeff

 

[doghead]

I'm pretty sure the heater control has a light bulb to illuminate it. I'll try to remember to check mine tonight.

The relay shown above, does it have 3 wires, blk, dk grn and orange? If so, that's the horn relay.

The diode in question, is shown in either figure F-1 or F-9 in the -20 tm schematics. I think you are showing the diode in F-1, it's for the water in fuel relay(if so).

 

[Stihl029]

The heater control does have a lamp to illuminate it, I just did all my dash lights while troubleshooting gen 2. My gen 2 is dim to the point where you do not notice it in day but at night its a bright red light.

 

[topgun217]

Got a question? Today I was tinkering. I pulled the instermment panel off to check bulbs. As I was putting the panel back in place, I noticed a small grey wire off dangleing. I believe it came off the light bulb socket for the voltmeter but it looked like it simply broke off or pulled out. I let it go and did'nt connect it back in. A few hours later I came out and put things back together w/o puting the grey wire back in place and then went to start the truck and she tried to turn over but acted like the batts had drained too low so she wouldn't start.

My ? is: Should I just push the grey wire into the back of the voltmeter and this will solve my problem?